Historical:Ogle Till Member
H. B. Willman and John C. Frye
The Ogle Till Member of the Glasford Formation was informally named the Ogle tills for Ogle County from exposures in western Ogle County (Frye et al., 1969, p. 24). It is herein formally named a member.
The Haldane West Section, NE NE NE Sec. 25, T. 24 N., R. 7 E., Ogle County, was designated the type section.
At some places the Ogle Till contains the Sangamon Soil in its top, and at many places it is overlain by Roxana Silt (Lanark Southeast, Lanark West Sections, table 7). At a few places the Ogle Till overlies the Kellerville Till Member, but more commonly it rests on bedrock or on a residual soil developed in bedrock. Further subdivision of the Ogle Member would appear to be appropriate when more data are available.
Extent and thickness
It has been intensely eroded and generally is less than 20 feet thick. The geographic extent of the member is shown in figure 6.
The Ogle tills were described as including three distinctly different till compositions and intercalated outwash of gravel, sand, and silt. Despite its range in mineral composition, the till of the Ogle Member is generally sandy, silty, tan to gray-brown, and interstratified with sand and gravel, characteristics that aid in distinguishing it from the more clayey, gray, compact till of the Sterling Till Member that overlies it. The composition of the Ogle Member is summarized in table 2.
Age and correlation
Although a definite age assignment of the Ogle Till has not been made, it is judged to be in the Monican Substage of the Illinoian Stage.
FRYE, J. C., H. D. GLASS, J. P. KEMPTON, and H. B. WILLMAN, 1969, Glacial tills of northwestern Illinois: Illinois State Geological Survey Circular 437, 47 p.
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